During the last CIEL conference, just after the marvellous chapel of Merton College Oxford had hosted a solemn EF High Mass, Professor Eamon Duffy observed as we walked along Merton Street to the Examination Schools that what he really found difficult about the EF Mass was that God's laos didn't get to say the Lord's own Prayer. It set me thinking.
What is the historical basis of this? I venture a suggestion. It was S Gregory the Great who moved the Pater noster to its Roman position immediately after the Canon, and the explanation which he gave to critics of this piece of blatant Byzantinisation seems to suggest that he thought it had a consecratory power, and so was best said 'over the Lord's Body'; i.e. in conjunction with the Canon (I hasten to add that there is quite a number of variant explanations of what the Pontiff meant). And consider the rite by which layfolk in the early centuries received communion extraliturgically from the host which they had brought home with them from the Sunday Mass. Having received the Lord's Body, they received also a cup of wine which was regarded not as the Blood of Christ but as an antitype of the Precious Blood. This chalice had been blessed by the lay communicant himself. We are not told what form of prayer of blessing he used, but Dom Gregory Dix was convinced that it was the Our Father. And that this is why in the Mass of the Presanctified the Lord's Prayer precedes the act of communion in which also, in the classical RomanRite, a cup of unconsecrated wine was drunk after the Lord's Body had been received.
One can see a sort of analogy here which might have inclined S Gregory to think that, just as when used by a layman the Pater noster would bless a symbol of the Precious blood, so, when used by a bishop, it might part of the formula for consecrating the reality of Christ's Blood. And if so, it might be most proper for the bishop alone to say such a prayer.